1. Field of the Invention
The invention relates to buttonhole controlling devices for a sewing machine.
2. Description of the Prior Art
Buttonhole controlling devices which a sewing machine operator may use to select the length of a buttonhole to be sewn and which are effective to cause a machine when in a buttonhole mode to automatically sew a buttonhole of the selected length are well known. While such a device may prove effective to cause neat buttonholes to be formed in one type of material, it may not produce the desired result in other fabrics. This is due to the fact that different materials vary in the extent to which they slip relative to the feed dog of a machine during sewing. As a consequence, buttonholes may be formed in which the stitching fails to close or in which the stitching extends beyond the desired point of closure.
It is a prime object of the present invention to provide a buttonhole controlling device which can be rendered effective regardless of the type of material being sewn to cause buttonhole stitching to close without overlap.